Underreamer.



Pavcented Mar. 4, |962. P. H. MACK- U NDERREMI EB (Appucazian ma .my 1d, 19m.)

(lo Model.)

UNITED STATES PATRICK H.A MACK, OF BRADFORD,

PENNSYLVANIA, ASSIGNOR TO OIL WELL SUPPLY COMPANY, OF PITTSBURG, PENNSYLVANIA, A COR- PORATION OF PENNSYLVANIA.

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UNDERREAMER.

SPECIFICATION forming part of Letters PatentNo. 694,400, dated March 4, 1902.

Serial No. 67,790. (No model.)

To all whom/ it may concern:

Be it known that I, PATRICK H. MACK, a citizen of the United States, residing at Bradford, in the county of McKean, State of Pennsylvania, have invented certain new and useful Improvements in Underreamers; and I hereby declare the following to be a full, clear, and exact description of the same, reference being had to the accompanying drawings, in which- Figure l is a view in elevation of an underreamer embodying my invention, a portion of the stock broken away and one of the cutters emitted to showmore clearly the form of the cutter-shank and the cutter-slot in the stock. Fig. 2 is a view in elevation at right angles to Fig. 1, one of the cutters omitted to more clearly show the shape of the cutterslot in the stock. Fig. 3 is a view of a portion of the stock in section on the line 3 3, Fig. 2, to show the cutter-slot and the relative arrangement of the cutters therein when expanded, the dotted lines indicating the position of the cutters when the reamer is within the casing. Fig. 4 is a sectional view of a portion of the stock similar to Fig. 3, the cutters omitted to more clearly show the cutterslot of the stock. Fig. 5 is a top plan view of one of the cutters, a second cutter being shown in dotted lines to indicate the relation of the cutters in the stock when two cutters are used. Fig. 6 is a side elevation of the cutter, the notch for reception of the pushpin being indicated in dotted lines. Fig. 7 is an end view of the cutter looking in the direction of the arrow, Fig. 6; and Fig. Sis

van inverted or under side view of the cutter.

Like symbols refer to like parts wherever they occur. Y y

In drilling oil, gas, and Artesian wells where the formation is soft or friable and caving from any cause is liable to occur the drilling is done through the casing which follows the dril1and a device commonly termedan underreamer follows the drill and precedes the casing to enlarge the drill-hole for the reception of the casing and to form a shoulder within the well for the support of the casing. This device, therefore, which is termed an underreamer, must be capable of expansion and contraction, so that it, with the drill, may be introduced and withdrawn through the casing, and as it is subject to rough usage, severe strains, and violent shocks it must be simple and exceedingly durable and strong, as the loss of a cutter Vwithin the well may mean the loss of the well and all outlay thereon up to the time of such an accident.

The object, therefore, of my present invention is the production of an exceedingly simple and strong underreamer, one wherein the stock and cutters and their union or combination is such as to effectively support and resist the blows, strains, and torsion incident to service; and to this end the main feature of my invention, generally stated, embraces the combination, with a reamer-stock having acutter-slot, with parallel bearings or abutments above and below and on opposite sides vof the vertical axis of the cutter-stock, of a pivoted cutter having a shank provided with oppositely disposed parallel bearing faces corresponding with those of the stock, whereby the cutter is supported by both the upper and lower faces of the cutter-slot, and the force of the blow is balanced about the axis in contradistinction to being concentrated on limited portions of the stock and eccentric to the axis thereof.

A secondary feature of my invention einbraces the combination, with a cutter and stock having the characteristics before noted, of a shoulder or projection on the cutter and. recess therefor on the periphery of the stock, whereby the inward thrust on the cutter is resisted and its pivot-pin relieved of strain.

There are other minor features of invention, all as will hereinafter more fully appear.

I will now proceed to describe my invention more fully, so that others skilled in the art to which'it appertains may apply the same.

In the drawings, 1 indicates a reamer-stock, which may be provided with the usual threaded pin la for attachment to the socket of a drill-cable, a socket 1b for the drill-pin, and the usual wrench-seats 1c. Ata suitable point in the stock 1 a cutter-slot 2 is formed through said stock, said slot having a horizontal or straight upper face 2 io receive a corresponding face on the shank of the cutter, an inclined lower face 2l on that side from which the cutter projects to allow of the inward swing of the cutter, so that the same may collapse when inserted in the casing, and a straight or square face 2c in a plane parallel with the upper face of the cutter-slot to receive the heel of the cutter-shank, whereby the cutter-shank will have a bearing support or abutment on the upper surface of the cutter-slot at a point close to the cutter, as at Qc, and asecond bearing or abutment on the lower surface ofthe cutter-slot and on opposite sides of the vertical axis of the stock, as at y, whereby the force is resisted by and disseminated throughout the stock 1 and the cutter strains have no leverage about the axis of the stock. Extending transversely of and at the periphery of the stock whence the cutter projects is a recess 2d to receive the upper end of the cutter and sustain it against inward thrust or torsion.

3 indicates the cutter, which is carried in the slot of the stock 1. This cutter may be of any suitable form, but is preferably in the form of a segment of a truncated cone, because such form will readily permit of re- Y forging and sharpening the cutter without liability of distortion or injury to the shank or part which enters the slot. It is provided with a stem or shank 3, which enters within the slot 2 of the stock, said shank having a straight upper and under edge or parallel edges to correspond with the upper and lower faces of the slot 2, the upper edge ofthe shank 3 being cut back or inclined at the heel to form a seat or recess for the reception of a spring-pressed push-pin, which projects the cutter 3 when it escapes from the casing. The shank 3 is of such width as the size of the slot 2 in the stock may demand and is determined by whether one or two cutters are employed and is joined to the cutter proper, so as to aiford a shoulder to allow the upper end 3b of the cutter to engage the recess 2d in the periphery of the stock above the slot, and the cutter-shank is so pivoted within the slot of the stock by a through-pin fi as to insure bearing-contacts and y and permit the drop of the cutter when inserted in th'eV casing.

In order to eiect the extension or projection of the cutter 3 when the same has passed from the casing, a push-pin 5, bearing on the heel of the cutter-shank, is employed, and said push-pin is carried in a pin-slot 1d, formed in the stock, being backed by a spring 5a, whose forcel can be increased or diminished at will by manipulating a screw-plu g 5b,wl1ich closes the pin-slot 1d.

The description given of the invention has been limited to a single cutter and the slot therefor, as such a construction may be adopted, ifvdesired; but preferably two oppositelyextending cutters are employed, as indicated in Figs. 2, 3, and of the drawings,- in which case the slot 2 of the stock, as above described, will be duplicated and reversed, the two slots, though connecting, being located on opposite sides of the axialplane of the stock, while the shanks 3fL of the cutters 3 will be reduced in width and correspondingly connected with the cutters, as indicated in Fig. 5 of the drawings. In other words, as the reamer shown, when cut by a plane parallel to its axis and to the contacting sides of the cutter-Shanks, will present a symmetrical View, the description of one cutter and its slot, which has been given, will sufce for both constructions.

Among the advantages incident to this invention are,iirst,simplicity and great strength to withstand rough usage, as the relative arrangement of the slots where two cutters are employed, as shown, reduces materially the width of the through-slot, leaving a bulk of metal to support the heel of each cuttershank, and an equal distribution of the metal on each side of any plane parallel to and passing through the axial center of the stock; second, effective support to the cutters and relief to the pivot-pin, as the force exerted on the cutter reacts upon the upper face of the slot at a point close to the cutter and on the lower face of the slot at the heel of the cuttershank, thus relieving the pivot of all strain, and the strains on the stock are taken in the line of its axis rather than as a leverage about its axis' or a cross bending strain; third, the cutter is supported against inward thrust and torsion as well as the pivot-pin relieved of the thrust, which is due to the engagement of the upper end of the cutter with the transverse recess in the periphery of the stock, and, fourth, the cutter may be reforged and sharpened without injury to or distortion of the cutter-shank which enters the slot in the stock.

Having thus described my invention, what I claim, and desire to secure by Letters Patent, is-

l. In an underreamer for oil and Artesian wells, the combination with a stock having a cutter-slot provided with upper and lower bearing-faces or abutments for the cuttershank said bearing-faces or abutments being on opposite sides of the vertical axis of the stock, of a pivoted cutter having a shank provided with upper and lower corresponding faces which engage the upper and lower bearings or abutments of the cutter-slot, substantially as and for the purposes specified;

2. In an underreamer for oil and Artesian wells, the combination with a stock having a cutter-slot provided with upper and lower walls or abutments for the cutter-shank said abutments being on opposite sides of the vertical axis of the stock, and a transverse peripheral recess for the head of thecutter, of a pivoted cutter having a head adapted to engage the recess in the periphery of the stock and provided with a shank having upper and lower bearing-faces adapted to engage the abutments on the upper and lower faces of IOO IIC

the cutter-slot; substantially as and for the purposes specified.

3. In an underreamer for oil and Artesian Wells, the combination with a stock having a cutter-slot provided with upper and lower walls or abutments for the cutter-shank said abutments being on opposite sides of. the vertical axis of the stock, of a pivoted cutter having a shank provided with parallel faces which engage the upper and lower walls or abutments ofthe cutter-slot, and a springactuated push-pin which bears on the heel of the cutter-shank, substantially as and for the purposes specified.

4. In an underreamer for oil and Artesian Wells, the combination with a stock having cutter-slots provided with a straight upper wall and oppositely-disposed abutments on the under walls which latter abutments are parallel to the upper walls of the slots, of two oppositely-disposed cutters having shanks provided with upper and lower bearing-faces which engage the upper and lower walls of the cutter-slot on opposite sides of the vertical axis of the cutter-stock, and a pivot-pin common to both cutter-Shanks; substantially asfand for the purposes specified.

5. In an underreamer for oil and Artesian wells, the combination with a stock having a cutter-slot extending therethrough the upper and lower walls of said slot being arranged to form an upper and lower bearing for the shanks of the cutters said bearings being on opposite sides of the vertical axis o f the stock,

of cutters provided with Shanks having upper and lower bearing-faces, a pivot-pin common lto the shanks of both cutters, and a spring- 

